Accuracy of fatal occupational injury registration in a high-income country: A comparison of two-source capture-recapture estimates with the number of cases identified in four register systems in Norway, 2000-2003

Background

Globally, work-related deaths (injuries and diseases) are a major social and public health problem. Register data on fatal occupational injuries in high-income countries may be considered to have high quality, especially when reporting is mandatory and regulated by law. We aimed to assess the accuracy of work-related injury death statistics in Norway, with reference to the Labour Inspection Authority and three other on-going registration systems (the cause-specific mortality register, the register for governmental compensations, and the register for insurance companies).

Methods

In this register-based study, we used the capture-recapture technique to adjust for undercounting. We investigated whether the capture-recapture method using two or three sources gave a valid estimate of fatal occupational injuries as compared with the number of cases identified in four registers administrated by the Norwegian Labour Inspection Authority, Statistics Norway, the Labour and Welfare Administration, and Finance Norway. The inclusion criteria were fatal unintentional injuries among residents of Norway between 2000 and 2003 that occurred while working for income in private and public land-based industries. We obtained ethical and legal approvals.

Results

In a period of four years (2000-2003), the Labour Inspection Authority registered 171 occupational injury deaths among residents employed in land-based industries. Two combinations of data sources gave capture-recapture estimates of 246 [95% CI 216; 279] and 265 [95% CI 234; 299] deaths. In total, 246 cases were identified in the four registration systems, which was 44% higher than the number of deaths registered by the Labour Inspection Authority. The Labour Inspection Authority had the most complete register out of the four registration systems.

Conclusions

The capture-recapture method used on two overlapping data sources gave highly valid estimates of the total deaths. We demonstrated the existence of significant weaknesses in the registration systems in a country considered to have high-quality register data.

Epidemiology of trauma: a population-based study of geographical risk factors for injury deaths in the working-age population of Norway

INTRODUCTION

Trauma is a major global cause of morbidity and mortality. Population-based studies identifying high-risk populations and regions may facilitate primary prevention and the development of optimal trauma systems. This study describes the epidemiology of adult trauma deaths in Norway and identifies high-risk areas by assessing different geographical measures of rurality.

METHODS

All trauma-related deaths in Norway from 1998 to 2007 among individuals aged 16-66 years were identified by accessing national registries. Mortality data were analysed by linkage to population and geographical data at municipal, county and national levels. Three measures of rurality (centrality, population density and settlement density) were compared based on their association with trauma mortality rates.

RESULTS

The study included 8466 deaths, of which 78% were males. The national annual trauma mortality rate was 28.7 per 100,000. Population density was the best predictor of high-risk areas, and there was a consistent inverse relationship between mortality rates and population density. The most rural areas had 52% higher trauma mortality rates compared to the most urban areas. This difference was largely due to deaths following transport-related injury. Seventy-eight per cent of all deaths occurred in the prehospital phase. Rural areas and death following self-harm had higher proportion of prehospital deaths.

CONCLUSION

Rural areas, as defined by population density, are at a higher risk of deaths following traumatic injuries and have higher proportions of prehospital deaths and deaths following transport-related injuries. The heterogeneous characteristics of trauma populations with respect to geography and mode of injury should be recognised in the planning of preventive strategies and in the organisation of trauma care.